Macroscopic Order and Electro‐Optic Response of Dipolar Chromophore–Polymer Materials

Abstract

This Minireview considers the key factors that govern the organization of macroscopic polarization in nonlinear optical systems obtained by electric poling of organic dipolar chromophores dissolved in polymer matrices. The macroscopic electric polarization depends on the thermodynamic state of the dipole system. The dependence of the paraelectric and antiferroelectric states of dipolar chromophores on the chromophore concentration and the strength of the poling field is discussed. Phase transitions between the para- and antiferroelectric states are investigated within the limits of the Ising and isotropic models for the chromophore dipoles and are considered for varying chromophore concentration, poling field strength, and macroscopic shape of the sample used for poling. The macroscopic polarization and electro-optic coefficient of the material change drastically upon phase transition. The theories are compared with the experimental data on the electro-optic coefficient dependence on the chromophore concentration. The isotropic dipole model shows excellent agreement with experiment for the chromophore systems most commonly used in nonlinear optics.

Multichromophores for Nonlinear Optics: Designing the Material Properties by Electrostatic Interactions

“…Similarly, attempts to orientate dipolar chromophores embedded in different matrices via poling techniques were less successful than expected 8. 47 In this case problems related to the orientation process47, 48 add to the effects of electrostatic interactions that in the poled sample may suppress the β response. So a careful study of intermolecular interactions helps to understand why progress in the preparation of good molecular materials for β responses was so frustrating.…”

Molecular Design and Supramolecular Organization of Highly Efficient Nonlinear Optical Chromophores for Exceptional Electro-Optic Properties

“…These results indicate that the improved dipole alignment and polar order might play a role in the enhanced r 33 values and improved poling efficiencies of the binary chromophore glass composites. The self-assembled chromophore matrices may act as pseudo-Ising lattices to help organize doped chromophores and improve their polar order (50). The physical and optical properties of molecular glasses and polymers based on chromophore 1-4 are summarized in Table 1.…”

Novel, side-on, PVK-based nonlinear optical polymers: Synthesis and NLO properties

“…However, the achievement of all of these requirements simultaneously presents a major obstacle, one of note being that high molecular nonlinearity (b) of a chromophore cannot be efficiently translated into high macroscopic NLO activity of a polymer. Generally, during the poling-induced noncentrosymmetric alignment of chromophores, which is required to secure macroscopic NLO effects, the poling efficiency of the materials is significantly reduced owing to the strong intermolecular, dipole-dipole interactions of the highly polar chromophore [12][13][14][15]. By controlling the shape of the chromophore moieties according to the site isolation principle, such interactions can be minimized and poling efficiency enhanced dramatically [16,17].…”